Recombinant yeast and method for producing ethanol using same

Abstract

Provided are excellent L-arabinose metabolic genes that function in yeasts. Provided is an L-arabinose metabolic gene cluster including an L-arabinose isomerase gene specified by a predetermined SEQ ID, an L-ribulokinase gene specified by a predetermined SEQ ID, and an L-ribulose-5-phosphate-4-epimerase gene specified by a predetermined SEQ ID.

1 . A recombinant yeast comprising a group L-arabinose metabolic genes including an L-arabinose isomerase gene, an L-ribulokinase gene, and an L-ribulose-5-phosphate-4-epimerase gene introduced thereinto, wherein
 the L-arabinose isomerase gene is a gene encoding any one of proteins (a) to (c) below:   (a) a protein comprising one amino acid sequence selected from the group consisting of SEQ ID NOs: 2, 4, and 6;   (b) a protein comprising an amino acid sequence having an identity of 80% or more to one amino acid sequence selected from the group consisting of SEQ ID NOs: 2, 4, and 6 and having L-arabinose isomerase activity; and   (c) a protein encoded by a nucleotide sequence that hybridizes with a nucleotide sequence complementary to one nucleotide sequence selected from the group consisting of SEQ ID NOs: 1, 3, and 5 under stringent conditions and having L-arabinose isomerase activity.   
     
     
         2 . A recombinant yeast comprising a group of L-arabinose metabolic genes including an L-arabinose isomerase gene, an L-ribulokinase gene, and an L-ribulose-5-phosphate-4-epimerase gene introduced thereinto, wherein
 the L-ribulokinase gene is a gene encoding any one of proteins (a) to (c) below:   (a) a protein comprising one amino acid sequence selected from the group consisting of SEQ ID NOs: 8, 10, 12, 14, and 16;   (b) a protein comprising an amino acid sequence having an identity of 80% or more to one amino acid sequence selected from the group consisting of SEQ ID NOs: 8, 10, 12, 14, and 16 and having L-ribulokinase activity; and   (c) a protein encoded by a nucleotide sequence that hybridizes with a nucleotide sequence complementary to one nucleotide sequence selected from the group consisting of SEQ ID NOs: 7, 9, 11, 13, and 15 under stringent conditions and having L-ribulokinase activity.   
     
     
         3 . A recombinant yeast comprising a group of L-arabinose metabolic genes including an L-arabinose isomerase gene, an L-ribulokinase gene, and an L-ribulose-5-phosphate-4-epimerase gene introduced thereinto, wherein
 the L-ribulose-5-phosphate-4-epimerase gene is a gene encoding any one of proteins (a) to (c) below:   (a) a protein comprising one amino acid sequence selected from the group consisting of SEQ ID NOs: 18, 20, and 22;   (b) a protein comprising an amino acid sequence having an identity of 80% or more to one amino acid sequence selected from the group consisting of SEQ ID NOs: 18, 20, and 22 and having L-ribulose-5-phosphate-4-epimerase activity; and   (c) a protein encoded by a nucleotide sequence that hybridizes with a nucleotide sequence complementary to one nucleotide sequence selected from the group consisting of SEQ ID NOs: 17, 19, and 21 under stringent conditions and having L-ribulose-5-phosphate-4-epimerase activity.   
     
     
         4 . The recombinant yeast according to  claim 1 , which overexpresses a galactose permease gene. 
     
     
         5 . The recombinant yeast according to  claim 4 , wherein
 the galactose permease gene is a gene encoding any one of proteins (a) to (c) below:   (a) a protein comprising the amino acid sequence of SEQ ID NO: 24;   (b) a protein comprising an amino acid sequence with an identity of 80% or more to the amino acid sequence of SEQ ID NO: 24 and having galactose permease activity; and   (c) a protein encoded by a nucleotide sequence that hybridizes with a nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO: 23 under stringent conditions and having galactose permease activity.   
     
     
         6 . The recombinant yeast according to  claim 1 , wherein a xylose isomerase gene is introduced. 
     
     
         7 . The recombinant yeast according to  claim 6 , wherein
 the xylose isomerase gene is a gene encoding any one of proteins (a) to (c) below:   (a) a protein comprising the amino acid sequence of SEQ ID NO: 26;   (b) a protein comprising an amino acid sequence having an identity of 80% or more to the amino acid sequence of SEQ ID NO: 26 and having xylose isomerase activity; and   (c) a protein encoded by a nucleotide sequence that hybridizes with a nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO: 25 under stringent conditions and having xylose isomerase activity.   
     
     
         8 . A method for producing ethanol, comprising
 a step of culturing the recombinant yeast according to  claim 1  in a medium comprising arabinose for ethanol fermentation.   
     
     
         9 . The method for producing ethanol according to  claim 8 , wherein
 the medium comprises cellulose, and   at least saccharification of the cellulose simultaneously proceeds with the ethanol fermentation.